1. Field of the Invention
The present invention relates to telecommunications. In particular, the present invention relates to a novel and improved method and system for minimizing message processing latency in a communication network.
2. Description of the Related Art
Internet Protocol (IP) has been widely used as an OSI (Open Systems Interconnection) network layer protocol in packet switched networks such as Internet for years. The most commonly used version of IP has traditionally been Version 4 (IPv4). A recently developed version, Version 6 (IPv6), is however also beginning to be supported. IPv6 includes the capabilities of IPv4 but provides also additional features. The most obvious improvement in IPv6 over IPv4 is that IP addresses are lengthened from 32 bits to 128 bits, thus providing for significantly larger amount of network addresses. In the following, IP will be used to refer to IPv6 unless otherwise specified.
Mobile IP is an extension to IP aimed to provide mobility support for IP. Using Mobile IP it is possible for a terminal device to move from one link to another without changing its IP address (as seen by the layers above IP) and yet be reachable. Mobile IP is being developed by IETF (Internet Engineering Task Force) and full specifications may be obtained e.g. from www.ietf.org. In the following Mobile IP will be used to refer to Mobile IP support for IPv6 (Mobile IPv6) unless otherwise specified and the term “Mobile IP network” will be used to refer to an IP network that supports Mobile IP.
Terminology related to Mobile IP used in the rest of this document will be described in the following. A node refers to a device that implements IP. A router refers to a node that forwards IP packets not explicitly addressed to itself. A link refers to a communication facility or medium over which nodes can communicate at the OSI link layer. An interface refers to a node's attachment to a link. A subnet prefix refers to a bit string consisting of a number of initial bits of an IP address. A packet refers to an IP packet having one or more headers and payload. A header comprises one or more fields. A flag refers to a field of one bit length. Thus a flag may have one of two values, either 1 or 0. One of these values is predetermined to be such that when a flag has that value, the flag is considered to be set, often this value is 1. A unit of data used to deliver information related to the protocols used is referred to as a message. Depending on its length a Mobile IP message may be transmitted in one IP packet or it may be divided in parts and the parts may be transmitted in separate IP packets.
A Home Address refers to an IP address assigned to a Mobile Node and used as the permanent or semi-permanent address of the Mobile Node. A Home Subnet Prefix refers to the IP subnet prefix corresponding to a Mobile Node's Home Address. A Home Link refers to the link on which a Mobile Node's Home Subnet Prefix is defined. Any link other than a Mobile Node's Home Link is referred to as a Foreign Link. Any IP subnet prefix other than a Mobile Node's Home Subnet Prefix is referred to as a Foreign Subnet Prefix. A Mobile Node refers to a node that can change its point of attachment from one link to another, while still being reachable via its Home Address. Movement refers to a change in a Mobile Node's point of attachment to an IP network such that it is no longer connected to the same link as it was previously. If a Mobile Node is not currently attached to its Home Link, the Mobile Node is said to be “away from home”.
A Correspondent Node refers to a peer node with which a Mobile Node is communicating. The Correspondent Node may itself be either mobile or stationary. A Care-of Address refers to an IP address associated with a Mobile Node while visiting a Foreign Link. The subnet prefix of this IP address is thus a Foreign Subnet Prefix. A Mobile Node may have multiple Care-Of Addresses at any given time but only one may be registered at the Home Agent. A Home Agent refers to a router on a Mobile Node's Home Link with which the Mobile Node has registered its current Care-Of Address.
Binding refers to the association of the Home Address of a Mobile Node with a Care-of Address for that Mobile Node. A Binding Update message is used by a Mobile Node to notify Home Agent and possibly also other nodes of a new Care-of Address for itself.
A Binding Acknowledgement message is used to acknowledge receipt of a Binding Update message.
When a node receives a message, it takes a certain amount of time for the node to process the message, i.e. there exists a certain processing latency. Total processing latency comprises handling time of input, data processing time and handling time of output. The handling time of input refers to the time it takes to parse an incoming message, i.e. to perform syntax checks, semantic checks and validity checks. The handling time of output refers to the time it takes to generate a corresponding outgoing acknowledgement message. The data processing time refers to the time it takes to perform the actual data processing the message requires. For example, if the message were a Binding Update message received by a Home Agent, the data processing time would comprise the time it takes to perform Binding Update authentication, Binding Cache look up, Binding Cache update, Binding Acknowledgement generation, Duplicate Address Detection, Neighbor Discovery and Binding Refresh Request generation.
FIG. 1 illustrates a typical prior art method for processing messages in a Mobile IP network. A message is received in phase 11 after which all the functionalities required for processing said message are executed at once, phase 12. Since the execution of some of these functionalities, especially those involving database transactions, takes a significant amount of time, processing latency results. After finishing the execution of the functionalities an acknowledgement message is transmitted, phase 13.
Neither current Mobile IP specifications nor implementations include any mechanism to optimize or minimize the perceived message processing latency. Yet, as Mobile IP networks will become more common, the amount of users will keep growing and load on single network nodes will keep increasing. Therefore message processing latency will need to be minimized to avoid delays perceived by users.
Thus there is an obvious need for an efficient solution providing a mechanism to minimize the perceived message processing latency.